IIS pretty much just works and if you can view the site locally from the server or your home LAN then this is not a configuration issue with IIS.
Possible reasons why you can't view it from over the net ...
1) Windows (or other 3rd-party) firewall is running on the server and is blocking port 80.
2) If you have a home network/LAN your home router is not configured properly for forwarding port 80 requests to the web server.
3) Your consumer/residential grade ISP blocks inbound port 80 as this violates your Terms of Service for running a server (very common).
4) You don't know the public IP address assigned by your ISP.
5) You don't have a domain name registered and/or it's not pointing properly to your public IP address.
6) You don't have a static IP (usually given with commercial ISP accounts) and you have a dynamic DHCP public IP address (common for residential ISP accounts). In this case you need something like a dyndns account to link your dynamic IP to a domain name.
FWIW ... you would have all of these same potential issues with Apache ...